Copper alloys such as brass are variously used for piping materials, building materials, electric and electronic devices, machine parts, and the like. In gaming tokens, keys, Western tableware, hardware for decoration and construction, and the like, a white (silver-white) color tone may be required. To cope with such requirements, copper alloy products are subjected to a plating process such as nickel-chrome plating. However, the plated products have the problem that the plating layer of the surface is peeled off with extended use, and there is a problem in the case of reuse, since when the plated products are re-melted the plating material mixes with the copper alloy and decreases quality. Thus, a Cu—Ni—Zn alloy representing a lustrous white color on its own has been proposed.
For example, in JIS C7941 (Non-Patent Citation 1), free-cutting nickel silver containing Cu (60.0 to 64.0 mass %), Ni (16.5 to 19.5 mass %), Pb (0.8 to 1.8 mass %), Zn (remainder), and the like is prescribed. In Japanese Patent Publication No. 2828418 (Patent Citation 1), a white-based copper alloy containing Cu (41.0 to 44.0 mass %), Ni (10.1 to 14.0 mass %), Pb (0.5 to 3.0 mass %), and Zn (remainder) is disclosed.    [Patent Citation 1] Japanese Patent Publication No. 2828418    [Non-Patent Citation 1] JIS Handbook Published by Japanese Standards Association